There is a memory device in which a memory hole is formed in a stacked body, in which an electrode layer functioning as a control gate in a memory cell and an insulating layer are alternately stacked on each other in multiple layers, a charge storage film is formed on the sidewall of the memory hole, and a channel body layer is then provided in the memory hole, thereby three-dimensionally arranging memory cells.
In this type of memory device, there is a U-shaped memory string structure having a pair of columns extending in a direction of stacking a stacked body including a plurality of electrode layers and a joining portion buried in a back gate and connecting the pair of the columns to each other.
Before forming the stacked body including the electrode layers, a recess (a space) is formed in a base layer to be the back gate, and a sacrificial film is buried in the recess. After this burying, the stacked body including the electrode layers is formed on the base layer, a hole for the column is formed, and the sacrificial film in the recess is removed through the hole by etching. After this etching, a charge storage film and a channel body layer are formed in the hole and the recess for forming a nonvolatile semiconductor memory device. In this type of nonvolatile semiconductor memory device, the number of stacked layers of the stacked body tends to increase more and more. Thus, an increase in the number of stacked layers of the stacked body sometimes causes the parasitic resistance of the channel body layer to increase. Desirably, the parasitic resistance of the channel body layer is more reduced.